Abstract

A recently identified class of myopathies is produced by abnormal desmin, and is characterized by a disorganization of the desmin filament network, the accumulation of insoluble desmin-containing aggregates, and destructive changes in the sarcomeric organization of striated muscles. The desmin filaments interact with various other cytoskeletal proteins. The distinct clinical phenotypes are heterogeneous, with progressive skeletal myopathy, cardiomyopathy, and respiratory insufficiency as the most prominent features. Most of the desmin mutations are autosomal dominant. Identification of the causal genetic mutations shows that the desmin gene is not the only gene implicated in desminopathies; other genes encoding desmin-associated proteins, such as alpha-B-crystallin, and synemin may also be involved. Patients with mutations in their alpha-B-crystallin gene, which produce similar skeletal and cardiac myopathies, also have opaque lenses. Knockout mice have helped to reveal the fundamental role of desmin filaments in cell architecture, sarcomere alignment, myofibril organization, and the distribution of mitochondria. Transgenic mice, which accumulate aggregates of desmin and associated proteins in their muscles, show that the loss of desmin intermediate function as a result of mutations in desmin itself, or in the desmin-associated constituents, is important for disease progression.